As one of imaging methods by an X-ray diagnostic apparatus, imaging using a stent is known. The stent is formed into a meshed tube using a strut having a structure like wires. Examples of typical stents used with an X-ray diagnostic apparatus include an intracranial stent.
The intracranial stent has a very thin strut. Therefore, it is difficult to observe the stent self by the X-ray diagnostic apparatus. Specifically, the strut of the intracranial stent has a cross-sectional diameter of approximately 60 μm. Accordingly, the conventional stent has markers so that a rough position of the stent can be known by imaging with an X-ray diagnostic apparatus. Specifically, four markers are arranged on a same circle forming one end of the stent at an equal interval. In addition, the other four markers are arranged at positions, on the other end side of the stent, derived by projecting positions of the four markers on the one end in the longitudinal direction.
Meanwhile, an X-ray diagnostic apparatus includes an X-ray detector having a high spatial resolution compared to an X-ray CT (computed tomography) apparatus. However, only markers can be observed mostly on a fluoroscopic image and an obtained image by an X-ray diagnostic apparatus. Note that, the strut of the stent can be observed by 3D (three dimensional) imaging.
By the way, the reproducibility not more than 100 μm of the rotation system and stasis of the strut are required for depicting the strut of the stent having a minute structure when a method of correcting a vibration using a vibration table acquired in the past, which is generally used for correction of a vibration or the like in 3D imaging by an X-ray diagnostic apparatus, is employed.
However, pressures placed on blood vessels near the stent changes due to the beat. Therefore, a motion due to changes in pressures of blood vessels sometimes occurs in the stent contacting the blood vessels. Further, it is sometimes difficult to keep a positioning error of a rotation system mounting an X-ray detector and X-ray tube under 100 μm in a conventional X-ray diagnostic apparatus.
Accordingly, an attempt to improve a stability of an X-ray diagnostic apparatus mechanically and an attempt to detect a minute change in position of a rotation system by a position sensor or the like so that the detected change in position can be corrected are made. However, these attempts bring a problem that a cost of X-ray diagnostic apparatus becomes high. Furthermore, it is sometimes difficult to observe a strut clearly because of a deviance of the strut due to a motion of an imaging part even though a displacement of a rotation system can be corrected entirely.
It is an object of the present invention to provide an X-ray diagnostic apparatus, an X-ray diagnostic method and a stent for an X-ray diagnosis which make it possible to depict a minute strut of stent by an easier way in imaging using the stent.